Condenser arrangement



July 18, 1939. L. F. WHITNEY v v ,1

CONDENSER ARRANGEMENT Filed Oct. 29, 1957 Patented July 18, 1939 UNITEDSTATES PATENT. OFFICE CONDENSER ARRANGEMENT Application October 29,1937, Serial No. 171,647

15 Claims. (01. 62-115) This invention relates to animproved condenserarrangement, and particularly to a compact arrangement of this characterwhich may be employed in a refrigerating system, such, for example, as asystem of the character disclosed in United States Patent No. 1,761,551to Eastman A. Weaver.

It is often desirable to provide a compact condenser which may, forexample, be installed in the upper part of a household" refrigeratorhousing without objectionably increasing the height of the housing.

A condenser of the type to which the present invention is directed mustbe arranged to drain condensed liquid to a suitable outlet or outlets.Such acondenser may comprise a single condensing duct into and throughwhich vapor passes; such a duct should have a general inclination tofacilitate drainage of the condensate and to prevent collecting of thesame in portions of the duct. For example, in refrigerating systerns ofthe character referred to, it appears desirable to have the ductprovided with a general inclination at least of the' order of 5. On the,other. hand, it is desirable to have a relatively long duct or passageto afford adequate cooling capacity, particularly when air cooling isemployed and the duct is provided with cooling fins or the like, I

If an elongate duct having a continuous inclination of the order namedis provided for the condenser, the total height of the condenser will begreater than is desirable in many household installations. Accordinglythe present invention affords an arrangement of the condenser. duct withsuccessive sections having an inclination at least of the order named,so that the duct may have an adequate length to afford proper coolingcapacity, while being arranged to afiord compactness.

To permit these desirable results, the duct preferably comprisessuccessive sections which are slightly inclined from the horizontal andwhich are substantially parallel to each other. Thus the condenser ductmay comprise a first section which is upwardly inclined from the lowerside or end to the upper side or end of the condenser, the duct beingcontinuedin a second section inclining downwardly in generalparallelism' to the first section, a third section. preferably beingconnected to the second section and inclined upwardly in substantialparallelism to the first two sections, and a fourth section iii--clining downwardly and being substantially parl allel to the first threesections. Thus the condenser duct may be arranged so that the condenserdoes not have an objectionable height or vertical dimension, while thepipe sections are arranged in general side-by-side relation, so that thecondenser may have horizontal dimensions permitting its readyinstallation in a conven- 'tional refrigerator cabinet.

In order to permit the arrangement of the duct sections in this mannerand yet to avoid pocketing of the condensate at the lowerend of thecondenser, drains are provided communicating with the lower ends of eachof the duct sections, so that condensate from any part of the condensermay be received by one or the other drains. Suchdrains communicate witha common outlet or condensate receiving pipe which directs the condensedrefrigerant from the condenser back tothe cooler or evaporator. Such anarrangement without' further qualification would be unsatisfactory whennon-condensable gases are received in the condenser; such gases wouldtend to pocket in the condenser cluct and the vapor would pass directlyfrom one drain to another rather than flowingthrough each of thesuccessive duct sections.

In order to prevent such undesirable results, trap means is provided toprevent the flow of vapor from one drain directly into another drain,although this meanspermits the flow of condensate from each drain 'tothe common receiv ing pipe. Thus the vapor received by the condenserpasses in succession through each of the condenser sections until it isliquefied, while the condensate may flow from each section to thecorresponding drain and from the latter to the common receiving pipe.

A condenser of this general type may also conveniently be provided witha drum connect ed to the last section or connected to the end of thecondenser remote from the vapor inlet, this drum having a substantialvolumetric capacity and thereby increasing the total effective volume,Of the condenser so that substantial changes in the temperature of thecondenser duct do not result from theappearance of non-condensable gasesin the system. Furthermore, such a drum or chamber aids the separationof the non-condensable gases from the vapor.

A system in which a condenser of this type is employed may operate atlow pressures and may be provided with a purger of the type disclosed inthe United States patent to Daniel F. Com-.

stock No. 1,892,869, issued January 3, 1933. Such a purger isarrangeckto receive non-condensable gases from the condenser, and toexhaust the ularly advantageous when freezing occurs in the refrigerantreturn pipe between the condenser and evaporator. Under such conditionsit is desirable that the condensate collect in the condenser withoutoverflowing from the same and returning in liquid form to the region ofthe pumping means or aspirator, which might result in the formation ofan undesirable sludge. Thus, for example, when water alone is employedas the refrigerant, the condenser may have a liquid capacity suflicientto receive all of the refrigerant in the system, while when ananti-freeze agent is employed,- the liquid-con taining capacity of thecondenser may be made somewhat smaller.

In the accompanying drawing:

Fig. 1 is a diagrammatic view of a refrigerating system provided with acondenser arrangement of the character afforded by the presentinvention, the condenser assembly being shown by an isometricdisclosure;

Fig. 2 is a plan view of the condenser assembly and related parts;

Fig. 3 is a view, partly in section and partly in elevation, of the trapassembly which is asso-- ciated with the condenser; and

Fig. 4 is an elevational detail of a portion of the condenser includingthe drum and the trap assembly.

While a condenser arrangement of the character disclosed herein may beemployed in different environments for various purposes, it isparticularly useful when employed with a refrigerating apparatus of thecharacter disclosed in the above-identified patents. Such an apparatusis diagrammatically shown in Fig. 1 and includes a boiler I providedwith a heating element 2 such as an electrical resistance factor. Theboiler I may contain a body of heavy propellant, such as mercury. Duringnormal operation mercury vapor flows from the boiler I through theriser.

3 to the aspirator nozzle 4, from which the mercury vapor passes at highvelocity into the mixing chamber 5. The latter is connected by a vaporduct 6 to a cooler I which contains a body of liquid refrigerant such aswater or a mixture of water and a suitable anti-freeze ingredient such,for example, as the mono methyl ether of ethylene glycol. The propellantvapor draws refrigerant vapor from the cooler 1 through the pipe 6 intothe mixing chamber 5. The mixed vapors pass into the funnel I where therefrigerant vapor is compressed and propellant vapox is condensed,suitable cooling fins, II or the like being provided to aid thecondensation of the propellant vapor. The compressed refrigerant vaporpasses through a duct l2 to a condenser 20 which may be disposed at theupper part of the system, while the condensed propellant is received bya drain M which is continued as one leg of a mercury containing trap Hi,the opposite leg of the latter being connected to the drop tube l6 of apurger, which receives non-condensable gases through a supply duct H.

The non-condensable gases are compressed by propellant globules droppingthrough the tube It as more fully disclosed in the above-identifiedpatent to Daniel F. Comstock, the compressed gas being exhausted fromthe system through the well or vat l8 and the propellant liquid risingfrom the lower part of the purger through the duct I9 to a spill-overconnection with the pipe 22 which is connected to the duct 23 leadingback to the lower part of the boiler. The upper end of the duct 23 mayconveniently be connected to the mixing chamber to receive condensedpropellant particles from the same. A column of the liquid propellant inthe return duct 23 balances the boiler pressure.

A duct 21 is provided with a trap 28 to receive propellant from thecooler I so that stray propellant particles may return from this portionof the system to the duct 22 and thence to the boiler I.

The condenser assembly, which more particularly forms the subject matterof the-present invention, may conveniently comprise a condenser ductwhich affords a continuation of the vapor duct |2. This condenser ductis provided with a plurality of sections which have a slight inclinationfrom the low to the high end of the condenser. Thus the first section 3|has its upper end connected by a U-shaped pipe portion 3| to the secondsection 32, the latter being connected by a similar connection 32 to thethird section 33, which in turn is connected by a U- shaped connection33 to a fourth section 34. The duct sections 3|, 32, 33 and 34 may bedisposed substantially parallel to each other and may each have amoderate inclination. In other words, each of the pipe sections and theU-shaped connections therebetween may lie in a common inclined plane.Each of the sections 3|, 32, 33 and 34 is provided with a plurality ofcooling fins 36. 1

It is evident that vapor received from the vapor inlet pipe l2 will passinto the first section 3|, flowing through this section from the lowerto the upper end of the condenser, thence through the connection 3| intothe second section 32, through which the vapor will flow downwardlytoward the lower end of the condenser, being received by the connection32. From the latter the vapor flows through the third section 33 fromwhich the vapor passes through the connection 33 into the fourthdownwardly inclined section 34. A suitable drum or receptacle 40 may beconnected to the end of the last section 34, the gasreceiving tube llextending downwardly into this drum and having an open end therein. Drum4|! preferably has a volumetric capacity greater than that of the duct.The volumetric capacity of the condenser including the drum may thus bereadily made greater than the capacity of the cooler, if desired, sothat the condenser may be able to contain all or a substantial portionof the liquid refrigerant included in the system.

In order to avoid pocketing of liquid in the lower portions of thecondenser, drains are provided to receive condensate from the lower endof each duct section. Thus a drain 42 is connected to the lower end ofthe duct section 3|, while a drain 43 is connected to the U-shaped pipeportion 32 at the lower ends of pipe sections 32 and 33. A third drain44 communicates with the bottom of the drum 40, thus being arranged toreceive condensate drained from the fourth section 34 into the drum.

The drains 42, 43 and 44 are arranged to supply the liquefledrefrigerant to a common receiving pipe 46 which is provided with a trap41 to hold a body of pressure balancing liquid, the

I side wall of which isconnected to the open end of the drain 44 (Fig.3). The drain 4! extends downwardly into the receptacle and has an .openend in the lower part of the same, while the receiving pipe 46 has anopen end communicating with the interior of the receptacle between itsupper and lower walls, the drain 43 conveniently communicating with thepipe 46 outside of the trap 50; The trap 50 contains a liquid body 51,,e. g., mercury, in which the lower end of the pipe 42 and the end ofpipe 44 are immersed; the pipe 48 having a general downward inclinationso that the level of the mercury in the cylindrical recep--' tacle iseven with the connection to this pipe.

is in operation, some mercury particles stray from the funnel ilflthrough the pipe lz-to the condenser 20 where these particles arecondensed. Some oi these particles are receivedby the drains 42 and 4d,the remainder thereof being received by the drain 43. The particlesreceived by the first-named drains pass .into the cylindrical receptacleso that the -heavy'liquid body 51 is always maintained in thisreceptacle. On the other hand, when the mercury tends to pile up in thereceptacle above its connection with the pipe 46, the mercury overflowsinto this pipe and drains to the trap 41. If the mercury in this trapoverflows, it is received by the cooler I and then by the trap 28, iromwhich the mercury passes through the pipe 21 to the ducts 22 and 23 andthus back to the boiler. Condensed mercury received by the drain 43passes directly to the pipe 46 and may similarly return from the latterto the boiler.

It is thus evident that the mercury body 51 is automatically maintainedat the desired height in the trap 50. Accordingly when the condensedrefrigerant is received from thedrain 42, it rises to the top of themercury body 51 and overflows into the receiving duct 46. Similarlycondensate from the drain 44 rises to the top of the mercury body andpasses into the pipe 46, while obviously condensate from the drain 43 isdirectly received by the pipe 46. a

The body of liquid mercury in the trap affords a seal preventing thedirect flow of refrigerant vapor between any of the drains 42, 43 and44.

.Accordingly vapor can not flow directly from the lower end of one drainto that oi. another and the main vapor stream passes by the drains andgoes through the successive duct sections where condensation occurs. Thenon-condensable gases which may appear in the system are pumped intothe-condenser duct; the vapor passing through the duct sweeps tnesegases into the drum 40, from which they are drawn through the tube I! tothe purger. were the trap 50 not provided, non-condensable gases presentin the vapor stream would be pocketed in the U-shaped duct portions,thus materially reducing the efficiency oi the condenser.

The drum 40 may have an adequate volume substantially to increase thetotal volumetric capacity oi the condenser, for example, a volume atleast nearly as great as that of the condenser pumps theg'ases to thedrum; the downward inclination' or the duct section" 34 also aids themovement of the gases from this part of the condenser to the drum. Thedrum ordinarily v.may contain a body oi non-condensable gas I mixed withrefrigerant vapor, the pressure of this vapor being less than that ofthe vapor in the duct and the temperature of the drum being lower thanthat of the duct. Thus little condensation is taking place in the drumand there I! is no necessity of providing this part or the condenserwith nns.

. As shown in Fig. 4, the drum ll may have a downwardly inclined lowerwall, thus providing.

'aj'lower portion in which the non-condensabie ltS gases, which aregenerally heavier than the vapor, may collect, it being evident that theopen end oi" tube I1 .is disposed adjoining this lower part of the drum,and that this part of -thedrum is below the adjoining 'part of thecontil When a system of the type. shown in.Fig. 1

denser duct. Such an arrangement permits a.

larger proportion of gas to be included in the therein may be lower thanthe temperature of the condenser duct. Accordingly the pressure oi therefrigerant vapor in the drum may be 8 substantially lower than thepressure of the reirigerant vapor in the condenser duct. Since I thetotal pressures of the vapor-gas mixtures in the duct and drum must besubstantially the same, the proportion of non-condensable gases as isgreater in the drum. Accordingly the mixture which is being supplied tothe purger is relatively rich in gas and weal: in vapor. Thus while someof the vapor may be exhausted by the purger,

the amount of vapor thus exhausted is negligible 0 even over a very longperiod of time.

Under'actual operating conditions the drum may contain non-condensablegases which, were the drum not provided, would fill a portion of thecondenser duct and thus reduce the length a of the duct then eflfectiveto cause condensation of the refrigerant vapor. Due to the increasedvolumetric capacity of the condenser resulting from the use oi the drum,a given quantity of gas does not'have such a tendency to require M anincrease in pressure and temperature in the condenser as would be thecase were the drum to be omitted.

It is thus apparent that the arrangement of the drum or'chamber 40permits the condenser 55 to be compact and yet to have adequatevolumetric capacity so that it is less sensitive to the leakage oinori-condensable gases than would otherwise be the case. The collectionor the gases in the drum is due both to gravity and to so the sweepingaction of the vapor stream, while, due to gravity, the mixture in thedrum itself is especially rich in gases adjoining the inlet of thepurger supply tube l'l.

Furthermore, it is desirable to have a con- 06 denser of adequatecapacity to retain all of the liquid refrigerant pumped thereto whenfreezing occurs in the pipe 46 between the trap 41 and the cooler andthus prevents the normal flow Under these of refrigerant back' to thecooler. conditions the system will continue to withdraw refrigerant fromthe cooler and pump the same to the condenser where condensate willcollect. It a refrigerant such as substantial pure water is employed inthe cooler, substantia all of the I refrigerant may thus be pumped tothe condenser which, under these conditions, should have a liquidcapacity sufficient to contain substantially all of the refrigerant inthe system without allowing the same to overflow from the condenser andreturn through the pipe I! to the lower end of funnel it). Such amovement of the liquid refrigerant might result in an interaction of-themercury and refrigerant to form sludge, such a sludge substantiallyimpairing the effectiveness of the system as more particularly describedin my copending application Serial No. 171,325, filed October 2'7, 1937.

When refrigerant including an anti-freeze agent such as methylcellosolve is employed in a system of this character and freezing occursin the pipe 46, the aspirator will continue to withdraw refrigerantvapor from the cooler, thus causing the COHECtiOIl of liquid refrigerantin the condenser. However, since the anti-freeze agent, e. g., methylcellosolve, is less volatile than water, the aspirator is not soeffective in pumping vapor from the refrigerant solution in the coolerand this solution becomes richer and richer in anti-freeze.

Eventually a condition of equilibrium is reached, so that little morevapor can be pumped,

by the aspirator, although some relatively rich solution remains in theevaporator. Accordingly it is evident that when an anti-freeze agentwhich is less volatile than water is employed in a system of thischaracter, the liquid capacity of the condenser need not be as great aswould be desirable when pure water is employed as the refrigerant. It issufficient, in a system employing such an anti-freeze agent, to providea condenser having adequate capacity to retain all of the refrigerantthat would be pumped thereto before the system reached the condition ofequilibrium just described.

When freezing occurs in the return duct 46 and the refrigerant collectsin the drum 40, the open end of the tube I] may be immersed in theliquid refrigerant. Under such conditions and without furtherqualification, the purger would then be effective in pumping liquidrefrigerant out of the system, which obviously would'be undesirable. Inorder to prevent such a result the tube ll adjoining the upper wall ofthe drum to is arranged in the general manner disclosed in the copendingapplication of Eastman A. Weaver, Serial No, 168,961, flied October 14,1937, the tube being provided with a vent or opening 10, and a wire Hpreferably is welded to the tube and extends diametrically across theopening. Thus when the lower part of the drum is filled with.

liquid refrigerant and the lower end of the tube is immersed in thisliquid, the purger can continue to'withdraw non-condensable gases fromthe system through the vent III, as more fully disclosed in theabove-identified Weaver application. During normal operating conditionsthe vent I0 is closed by a body of the liquid condensate so thatnon-condensable gases then only enter the tube I! through the lower openend thereof.

It is evident that the present invention, which provides a compactarrangement of a condenser duct, is particularly advantageous with anaircooled condenser for a refrigerating system, permitting the compactinstallation of the condenser in the upper part of a refrigeratorhousing, while permitting the ready drainage of liquid from all parts ofthe condenser and avoiding pocketing of liquid or non-condensable gasesin the same.

Furthermore, the present invention provides a condenser which hasrelatively high efficiency and yet suflicient volumetric capacity sothat it is not unduly sensitive to the leakage of non-condensable gasesinto the system either from the metal of the walls thereof or from theexterior atmosphere. The provision of the drum permits the compactcondenser with its relatively smalldiametered condenser duct to haveadequate capacity to receive all of the liquid refrigerant in thesystem. Accordingly, even when non-condensable gases collect in thesystem slightly faster than they are being exhausted by the purger, thesystem can continue to operate for a long period of time without anundue rise in the temperature and pressure of the condenser,

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modificationsand equivalents which fall within the scope of the appended claims.

I claim:

1. A condenser comprising a duct having a vapor-receiving inlet, asection of the duct having a general inclination upwardly from theregion of the inlet to a higher region, a second section of the ductcommunicating with the first section in said higher region and incliningdownwardly to a point near the level of said inlet, and drain pipescommunicating with the lower ends of each of said sections to receivecondensate therefrom.

2. A condenser comprising a duct having a vapor-receiving inlet, asection of the duct having a general inclination upwardly from theregion of the inlet to a higher region, a second section of the ductcommunicating with the first section in said higher region and incliningdownwardly therefrom, drains communicating respectively with the lowerends of each of said sections to receive condensate therefrom, areceiving pipe connected to said drains, and trap means preventingdirect flow of vapor from one drain to the other drain while permittingcon-- densate from both of said drainsto be received by said receivingpipe.

3. A condenser comprising a duct having at least four similarly inclinedsections, the first section having a vapor inlet at its lower end andcommunicating at its upper end with the upper end of the second section,the third section communicating at its lower end with the lower end ofthe second section and at its upper end with the upper end of the fourthsection, drains com- -municating with the lower ends of each of saidsections to receive condensate therefrom, a liquid containing trapconnected to at least two of the drains and arranged to prevent directflow of vapor from one drain to another drain, but to permit the flow ofcondensate from the drains, and a collecting pipe to receive saidcondensate from the trap and drains,

4. A condenser comprising a duct having, at least four similarlyinclined sections, the first section having a vaporinlet at its lowerend and communicating at its upper end with the upper end of the secondsection, the third section co'mmunicating at its lower end with thelower end of the second section and at its upper end with the upper endof the fourth section, a drain connected to the lower end of the firstsection to receive condensate therefrom, a second drain connected to thelower ends of the second and third sections, a third drain connected tothe lower end of the fourth section, a trap containing a 2,166,1 oo bodyof liquid, the first and one of the other drains having outlets in saidtrap below the surface of said body of liquid, a collecting pipeconnected to said trap above the level of said body of liquid andconnected to the third drain, whereby vapor is prevented from flowingdirectly from one drain to another drain.

5. A condenser comprising a duct having a plurality of similarlyinclined straight sections, the first section having a vapor inlet atits lower end, the successive sections being connected to each other bysubstantially U-shaped portions of the duct, said straight sections andu-shaped portions being substantially disposed in a common inclinedplane, whereby vapor passes upwardly and down-- wardly throughsuccessive sections of the duct, drains communicating with the lower endof each section to receive condensate therefrom and from the lJ-shapedportions, a common receiving pipe to which the condensate is directedfrom said drains, and a liquid-containing trap communicating with the.drains and pipe, said trap permitting the flow of condensate from saiddrains'to the pipe, but preventing the flow of vapor directly from onedrain to another drain. 6. A system of the class described employing.

the vapor of a heavy propellant which pumps refrigerant vapor from acooler to a condenser, said system having means to condense the majorportion of the propellant while supplying the pumped refrigerant vaporwith stray propellant particles to the condenser, said condensercomprising a duct having a plurality of similari y inclined sections,the first section having an inlet at its lower end to receive thepumpedrefrigerant vapor and stray propellant particles, the successivesections of the condenser being substantially disposed in a commoninclined plane, drains communicating with the lower end of each of saidsections to re-= ceive condensate therefrom, a common receiving pipe towhich the condensate is directed from said drains, a liquid-containingtrap communicating with the drains and pipe, said trap containing a bodyof the heavy-propellant liquid and being arranged to permit the flow ofcondensate from the drains to the pipe, but preventing the flow of vapordirectly from one drain to another drain.

7. A condenser comprising av duct having at lease four similarlyinclined sections, the first section having a vapor inlet at its lowerend and communicating at its upper end with the upper end of the secondsection, the third section communicating at its lower end with the lowerend of the second section and at its upper end with the upper end of thefourth section, drains communicating with the lower ends of each of saidsections to receive condensate therefrom, a liquidcontaining trapconnected to at least two of the drains and arranged to prevent directflow of vapor from one drain to another drain, but to permit the flow ofcondensate from the draine a collecting pipe to receive said condensatefrom the ,trap and drains, and a chamber connected to the end of saidfourth section to receive non-condensable gases.

8. A condenser comprising an elongate condensing duct of relativelysmall diameter, cooling means associated with the duct, said duct havingan inlet end to receive ccndensable vapor, a chamber having a connectionwith the end of said duct remote from said inlet, said chamber having aportion at a lower level than that of its connection to said duct,portion, whereby non-condensable gases may be swept by the vapor streamto said chamber, and the mixture of vapor and gases in said chamberportion may be richer in said gases due to the different weights of thevapor and gases, and a gas outlet pipe communieating with saidchamberportion.

9. A condenser comprising an elongate condensing duct, cooling finsassociated with said duct, said duct having an inlet to receivecondensable vapor, a chamber, a connection between said chamber and theend of the duct remote from its inlet, said chamber being free from finsand having a portion at a lower level than that of said connection, saidportion being arranged so that a mixture of vapor and non-condensablegases which is relatively rich in the gases may pocket therein due tothe different weights of the vapor and gases, and a gas outlet pipecommunicating with said portion of the chamber at a level substantiallylower than said connection with the duct, whereby a mixture rich in gasmay be pocketed in said chamber portion and preferentially supplied tosaid outlet pipe.

10. A system of the class described, comprising a refrigerant circuitincluding a cooler and a condenser, said condenser receiving refrigerantvapor and non-condensable gas which has a weight greater than that ofthe vapor, said condenser comprising a condensing duct portion having aninlet end, and a gas collecting chamber having a connection with theopposite end of the duct portion, the major portion of the chamber beingdisposed at a level lower than the connection to said duct portion,whereby a mixture of vapor and gas which is relatively rich in gascollects in said portion'of the chamber.

11. A system of the class described comprising a. refrigerant circuitincluding a cooler and a condenser, said condenser receiving refrigerantvapor and non-condensable gas which has a weight greater than that ofthe vapor, said condenser comprising a condensing duct portion having aninlet end and a gas collecting chamber having a connection with theopposite end of the duct portion, said chamber having a volume which isat least substantially as large as that of the duct portion, the majorportion of the chamber being disposed below its connection torsaid ductportion, whereby a mixture of vapor and gas which is rela-' tively richin gas coliects'in said portion of thechamber, and a purger connected tothe lower portion of the chamber to receive non-condemsable gasestherefrom.

12. A low pressure system or the class described employing the vapor ofa heavy propellant to pump refrigerant vapor from a cooler to acondenser, said system having means to condense the major portion of thepropellant While'supplying the pumped refrigerant vapor with stray pro--pellant particles to the condenser, said system also having a purgerwherein condensed pro-- pellant pumps non-condensable gases from thecondenser, said condenser comprisinga duct having a plurality ofsimilarly inclined sections, the first section having an inlet at itslower end to receive the pumped refrigerant vapor and stray propellantparticles, drains communicating with the end of the condenser ductremote from its inlet end, said drum havinga volumetric capacity greaterthan that of the duct and having its major portion disposed ata levelbelow its connection to the duct, a tube connecting the lower portion ofsaid drum to the purger so that a mixture rich in non-condensable gasesmay be supplied from the condenser to the purger.

13. A low pressure system of the class described employing the vapor ofa heavy propellant to pump refrigerant vapor from a cooler to acondenser, said system having means to condense the major portion of thepropellant while supplying the pumped refrigerant vapor with straypropellant particles to the condenser, said system,

also having a purger wherein condensed propellant pumps non-condensablegases from the condenser, said condenser comprising a duct having aplurality of similarly inclined sections, the first section having aninlet at its lower end to receive the pumped refrigerant vapor and straypropellant particles, drains communicating with the lower ends of thesections to receive condensate therefrom, a common receiving pipe towhich the condensate is directed from said drains, a trap communicatingwith the drains and pipe and containing a body of the heavy propellantliquid, said trap being arranged to permit the flow of condensate fromthe drains to the pipe but preventing the flow of vapor directly fromone drain to another drain, and a drum connected to the end of thecondenser duct remote from its inlet end, said drum having a volumetriccapacity greater than that of the duct and having its major portiondisposed at a level below its connection to the duct, a tube connectingthe lower portion of said drum to the purger so that a mixture rich innon-condensable gases may be supplied from the condenser to the purger,said condenser having a volumetric capacity suflicient to receive all ofthe liquid refrigerant in the system so that the refrigerant may becontained in the condenser when refrigerant freezing in the receivingpipe prevents the normal circulation of the refrigerant through thesystem.

14. Refrigerating apparatus of the class described comprising apropellant circuit and a refrigerant circuit including a condenser, acooler,

and a pipe connecting the condenser to the cooler, said circuits havinga part in common where propellant vapor entrains refrigerant vapor fromthe cooler and pumps the same to the condenser, said system also havinga purger wherein condensed propellant pumps non-condensable gases fromthe condenser, said condenser including a condensing duct of relativelysmall diameter having an inlet end to receive vapor from the common partof the circuits, said condenser also including a drum with a relativelylarge volumetric capacity connected to the opposite end of the condenserduct, a tube to supply non-condensable gases from the drum to thepurger, said condenser having a liquid-retaining capacity great enoughto hold substantially all of the refrigerant pumped thereto whenrefrigerant freezes in the pipe between the condenser and the cooler,the drum providing a reservoir to receive non-condensable gases andpermitting the condenser to have adequate volumetric capacity.

l5. Refrigerating apparatus of the class described comprising apropellant circuit and a refrigerant circuit having a part in commonwhere propellant vapor pumps and compresses refrigerant vapor and wherethe propellant vapor is, condensed, said propellant circuit alsoincluding a boiler, a vapor pipe connecting the boiler to said commonpart, and a return pipe connecting said common part and the boiler, saidrefrigerant circuit also including a cooler and a refrigerant condenserwith ducts connecting said common part to the refrigerant condenser,said condenser to the cooler, and the cooler to said common part, saidrefrigerant condenser having a liquid capacity large enough to hold allof the refrigerant in the system whereby, when freezing occurs in theduct connecting the condenser and cooler,- liquid refrigerant maycollect in the condenser without flowing into the duct between saidcommon part and the condenser.

LYMAN F. WHITNEY.

